Fish pens are used in the commercial fishing industry to contain marine life, such as fish and shellfish, in their natural, open-water, environment. By containing fish in fish pens they can be readily raised and harvested. Many fish pens include some type of floating horizontal frame member from which a closed net that actually defines the pen space is suspended. Some fish pens are further provided with some type of netting that is suspended from the frame at or above the waterline. This netting prevents marine life from jumping over the frame to either enter or leave the pen and serves as a barrier that prevents birds from entering the fish pens and preying on the fish being raised therein.
While current fish pens are useful, there are some limitations associated with their use. Large waves, the type that develop during foul weather, can be intense enough to break apart the frames that form the skeletal structures for these pens. Normally sized waves, the type that are always present in the ocean, continually move the frames and any ancillary floats up and down. This repetitive movement continually stresses the pen netting and the associated frame members to which the netting is attached. If a pen is subjected to this movement for a long enough period of time, and the range of movement is wide enough, the netting and associated frame members may become stressed to the point where either the net rips or the frame members fracture. Moreover, still another disadvantage of these pens is that the frame prevents personnel from using tender vessels to enter the center area of the pen. Consequently, personnel are limited to tending the contents of the pen from around its outer perimeter as defined by the frame.
One alternative to the conventional frame-and-net pens is a spar-buoy pen as described in the applicant's assignee's U.S. Pat. No. 5,007,376. The pen of this disclosure includes a net that is suspended from at least three vertically oriented spar buoys. Each buoy is connected to a separate anchor assembly. The anchor assemblies are arranged to urge the individual spar buoys away from each other. Since the spar buoys are pulled away from each other, they cooperate to hold the net in an open state so as to define a pen for containing marine life. The pen of this assembly has a number of advantages over the previous pens that include a horizontal frame from which the pen nets are suspended. Since this pen does not include horizontal frame members, small tender vessels can cross the net so that the contents of the pen can be tended from the center of the net.
While the multispar-buoy pen has advantages over conventional, floating frame-type pens, there are some limitations associated with its use. For example, there are occasionally instances when wave motion can cause two buoys to move out of synchronization with each other. When this happens the lines connecting the buoys, including the actual net, may be stressed to the point where they break. Should this happen, the net will open to the sea and the marine life therein will be able to escape. Consequently, multispar buoys are not normally installed in locations where the buoys are regularly induced into this type of motion.